Table of Contents

Overview

Florida's Sea Level Is Rising

And It's Costing Over $4 Billion

The sea level around Florida is up to 8 inches higher than it was in 1950.1 | 2 This increase is mostly due to ice melting into the ocean and, complicated by the porous limestone that the state sits on, it’s causing major issues. Many traditional methods to solve for sea level rise and flooding in Florida won’t work, because water can flow through the porous ground, up from below, and under sea walls. In Miami-Dade County, the groundwater levels in some places are not high enough relative to the rising sea levels, which has allowed saltwater to intrude into the drinking water and compromised sewage plants. There are already 120,000 properties at risk from frequent tidal flooding in Florida.3 The state is planning over $4 billion in sea level rise solutions, which include protecting sewage systems, raising roads, stormwater improvements, and seawalls.

Sea level rise is speeding up

The sea level around Virginia Key, Florida, has risen by 8 inches since 1950. Its speed of rise has accelerated over the last ten years and it’s now rising by 1 inch every 3 years.2 Scientists know this because sea levels are measured every 6 minutes using equipment like satellites, floating buoys off the coast, and tidal gauges to accurately measure the local sea level as it accelerates and changes.4

Created with Highcharts 6.2.0

Sea level measurement from Miami area tide gauge since 1950

Causes & Complications

Why Are Sea Levels Rising?

While there are four causes of sea level rise in Florida, melting ice from the North and the South Poles and slowing of the Gulf Stream are the two largest contributors. Because the rate of ice melt has been increasing significantly since 1992,5 and the fresh water melting into the ocean has been slowing down the Gulf Stream,6 Florida is particularly vulnerable to an increased rate of sea level rise in the future. To learn more about these causes, click here.

How A Slowing Gulf Stream Increases Sea Level Rise

How Ice Melt Contributes to Global Sea Level Rise

Most flooding happens during the fall

In Florida, this is when the combined gravitational pull of the moon and the sun pulls water inland and when the Gulf Stream slows, which allows the water to rise even more. This causes unusually high tides called king tides. In places like Southeast Florida, king tides are typically nearly a foot higher than normal tides.1 Add that to the 8 inches of sea level rise since 1950, and you end up with flooding even on sunny days.

Solutions aren’t simple

In Florida, the bedrock beneath the state is porous limestone, which acts like a hard sponge full of holes and allows groundwater to rise at the same rate as the ocean. This can make flood mitigation efforts complicated, as some traditional methods won’t work. Water can flow through the porous ground, up from below, and under sea walls.

Sea level rise presents diverse, complex challenges to southeast Florida, with flooding and water-supply impacts that extend from the coast to the Everglades.

Forecast

What's the Future of Sea Level Rise?

In the last decade, the speed at which Florida’s sea level is rising has increased and is now rising by as much as 1 inch every 3 years.2 Around Miami, it took around 31 years for the sea level to rise by 6 inches.2 Scientists now forecast that in just the next 15 years, the sea level will have risen by another 6 inches.7

Scientists are not certain how fast the ocean will warm and ice will melt. They expect water levels to continue to rise faster, but are not sure just how fast. Therefore scientists from the National Oceanic and Atmospheric Administration (NOAA) and the US Army Corps of Engineers (USACE) have made predictions based on ranges from low to high.

Below you can see the range of the NOAA and USACE high and intermediate forecasts for various locations around Florida.8 Currently, the USACE high forecast, seen as the darkest red line, is the most likely projection.

Miami Beach

Created with Highcharts 6.2.0Miami Beach Sea Level Rise Forecasts

In 30 years Florida will see many more days of flooding, stronger storms, more extreme weather, and stagnant or declining coastal property values.

Flooding

Why Are Floods More Frequent?

When the ocean rises high enough, high tides cause flooding even on sunny days. Even though the sea level has only risen by around 3 inches, tidal flooding has increased by 352% across Florida since 2000.9

How sea level rise effects Florida

Flooding even when there’s no rain

Drainage systems are designed to channel excess rainwater from the streets and drain it into the sea. But with the pressure from rising sea levels and higher tides, seawater can get pushed into these pipes and spill out into the streets. This causes flooding even on days without rain.

Drainage Under Normal Tidal Conditions

Drainage With King Tide / Sea Level Rise

Increased storm surge flooding

Unfortunately, slightly higher sea levels make hurricanes even more damaging. Just a few more inches of sea level rise allow a hurricane to push more water onto the land, even if the hurricane itself doesn’t make landfall.

Hurricane Irma, 2017

Higher sea levels create a higher launching point for storm surge. These small changes in sea level rise are enough to turn what were 100-year storm surges into much more frequent events. In fact, in a third of 55 coastal sites studied throughout the US, 100-year storm surges will be 10-year or more frequent events by 2050.10

This means that in many coastal cities, if you bought a house with a 30-year mortgage today, by the time you paid off your mortgage you could be experiencing extreme 100-year storm surges ten times more frequently due to sea level rise alone. This does not include the added risk of more intense storms resulting from warmer water and a warmer atmosphere, which could further increase storm surge damage.

In 2017, Hurricane Irma made landfall in Cudjoe Key as a Category 4 Hurricane. Irma caused over $50 billion in damages and destroyed 25% of the Keys.11 Without sea level rise, Hurricane Irma’s 8 foot storm surge would have been lower.12

Hurricane Irma, 2017

Costs

What's at Risk in Florida?

There’s a lot at risk from sea level rise and flooding in Florida. When sea levels rise and water spills over into the streets, it puts not only homes and cars at risk, but can cause roads to be shut down and prevent access to important infrastructure like schools and hospitals. As the ocean rises higher, the salty water from it can mix with drinking water, ruining water wells. It can also make sewage systems back up into the streets, creating health hazards. In Miami-Dade County, the groundwater levels in some places are not high enough relative to the rising sea levels, which has caused saltwater to intrude into the drinking water.13 In Southeast Florida, there are 12 wastewater treatment plants with property 1-3 feet below the current sea level, which is still rising.14

Roads

Drinking Water

The ocean is salty, and as it rises higher, that salty water sometimes will mix with drinking water, ruining water wells.

Sewage Systems

High seas mean more underground pressure on sewage systems. If these systems are damaged, it can be a costly and smelly problem as well as a health hazard.

In Miami Beach there are 1,185 residential properties already at risk from repeated tidal flooding, by 2033 that number will increase to 3,890 as sea levels rise. In Hollywood, 2,104 properties at risk will turn into 3,548 within 15 years. In Saint Petersburg there are 3,140 properties at risk, which will become 4,545. And in Fort Lauderdale, there are 1,266 properties at risk, which will increase to 3,205 by 2033. To explore other coastal areas in Florida that are at risk at FloodiQ.com, click here.

Florida is spending over $4 billion

Some cities have sufficient resources to deal with this problem while others do not. Florida will need solutions at the individual, local, state, and federal levels to protect its coastal communities.

Miami Beach

Miami Beach has allocated $400 million towards seawalls, pumps and raising roads in their plan.15

Fort Lauderdale

Fort Lauderdale has developed a $1 billion stormwater plan to deal with increasing flooding.16

Broward County

Broward County has developed a $250 million plan to protect sewage systems from flooding.17